Thanks.
So I have noticed some sag already, so I ordered these: https://www.amazon.com/dp/B07VLLKX32
They will go into the frame above each enclosure. I'll drill a hole through the top of the enclosure, and bolt into those threaded inserts. If it's how I imagine, it should work perfectly, and be easily removable, if i want to take the enclosures in and out.